A problem in the mining and the construction of tunnels and other underground facilities in rock consists of that the roofs, walls and the like need to be strengthened so that they are prevented from collapsing down or recorded. In order to prevent parts of the mountain caves in through times several different types of devices and procedures to enhance the mountain has been developed.
A more modern example of these devices is different types of force-absorbing rock bolts and the like. A rock bolt preferably consists of an elongated body which is inserted in a hole drilled in the rock. After the elongated bolt is introduced into the hole in the rock is expanded in relation to the holes walls. Through this kind of construction collapse from the ceiling, walls and the like can be prevented.
Although existing rock bolts reduces the risk of collapse and the like, there are problems with existing types of rock bolts. One problem is posed by the existing bolts are usually time consuming to connect to the mountain. For example, existing rock bolts and the like require these to be anchored (the gate, to be fitted) with any type of encapsulation such as cement, polymeric materials, or the like. These procedures have the disadvantage that they take time to prepare, apply and solidify and/or a health hazard for construction workers to use. Some types of potting can also cause other types of adverse environmental impacts. A further problem with the use of rock bolts is present at mining. In mining operations the rock moves dynamic. The dynamic movements of the rock are increasing with the depth.
Using existing rock bolts, which connect with the castings, and similar to the rock, causes problems when these only to a limited extent the dynamic movements in the rock. There is thus a need for rock bolts were construction allows dynamic changes in the rock. In mining operations, there is need for the installation of, composition of, rock bolts shall be made with such a rational procedure and rock bolts as possible. It is therefore desirable that the roof bolts to be fitted by machine. This requires that the rock bolt has a construction which is suitable for this purpose. Most of the previously known constructions of rock bolts have the disadvantage that they cannot be installed efficiently by machine. There is thus a need for structures which can be effectively installed with machines.
There are also problems with existing types of rock bolts comprise a plurality of parts, which means that these can be complicated to manufacture and thus also expensive to manufacture and thus also buy. The known rock bolts can also cause that several different types of equipment is needed for the installation.
At the reinforcement of rock with a rock bolt of the type intended to be molded is generally used a so-called cam rock bolt, that is, a rod of solid steel, like steel reinforcements for concrete in each portion is provided with engagement means or anchor in the form of in radial direction extending cams (ribs/fins) extending in the short transverse direction. The rock bolt is inserted into one of the rock material absorption wells. Said bore has pre-filled with potting compound so that cam rock bolt enclosed with encapsulation in the borehole. At the borehole mouth cam rock bolt is equipped with end fittings, usually in the form of a nut and washer, which is applied to the area of the rock material surrounding the mouth of the drilled hole and with which the end fitting rock bolt can be given a certain degree of tension.
One known type of bolt consists of the so called “Kiruna bolt” whose distinguishing features is that it is a combination of a cam rock bolt and one in the rock mechanically fastened bolt. The rock bolt is intended to be infused in a borehole and in radial direction have extending cams which act as anchors in the molding composition. The “Kiruna bolt” further comprises end fastening device in its front end of the bolt for mechanical anchoring of the rock bolt in the bottom of the borehole. By cam rock bolt to some extent biased and to some extent carry load before the grout.
The patent SE5356927 of LKAB applicants disclosed a variant of a rock bolt which is intended to be molded into a borehole. The construction comprises in its front end section of a mechanical effective anchoring device comprising a wedge and is arranged so that the rock bolts attachment to a certain extent to be held by the expanded anchor rod. The structure further includes an elongated middle portion which includes a barrier which defines a predetermined area of the intermediate portion engaging means from contact with the molding composition in the borehole. The construction has several flaws and has the disadvantage that it takes time to install.
The patent EP0064362 of the applicant Neste O Y described a variant of a rock bolt which in its front end section comprises a wedge construction. The design differs materially from the present invention's construction.
The patent WO2006034208 describes a variant of a rock bolt comprising at least an elongated body such as a rod. The structure further includes at least one expandable body for anchoring rock bolt in a hole drilled in the rock. The structure further includes at least a clamping device which is used partly to expand the body and also used to bias the rock bolt against the rock. The rock bolt comprises at least a first taper, and at least a first wedge device. The construction in accordance with Patent them to a significant extent from the construction in accordance with the present application. For example, lacks the structure in accordance with the patent, an expandable wedge device with which the bolt is initially connected to the bore and then a second expandable wedge device is then caused to expand in the bore when the rock bolt is biased against the rock. The construction according to WO2006034208 is further difficult to install the machine which means that this probability is mounted manually. This should be seen in contrast to the construction in accordance with the present application which is preferably designed to be mounted (set) by machine. The design also has the disadvantage of this includes threads which are sensitive to dirt or the like. The construction is also less cost efficient in accordance with the construction according to the present patent application.
The construction in accordance with Patent WO2006034208 the same security as with the construction according to the present invention is not achieved. This is caused by the structure comprises solely a function to expand the expandable body.
The patent WO2004001192 describes a variant of a system comprising at least a rock bolt. The construction in accordance with the patent differs to a significant extent from the construction in accordance with the present application. For example, the structure in agreement with the patent WO2004001192 hardly is mechanized. The design requires probably encapsulation is used to secure the bolt to the mountain.
The patent US2007031196 describes a variant of a rock bolt. The rock bolt comprising an elongate body which in one embodiment, a use at least a first taper, and at least a second taper which expand at least one expandable body. The construction in accordance with the patent differs to a significant extent from the construction in accordance with the present application. The expandable body includes, for example, an expandable body of elastic material such as a plastics material, so that the structure of substantially smaller extent can absorb forces than rock bolt in accordance with the present application. The structure further includes screw expanders which are considerably more sensitive to drill ester in the hole than the construction in accordance with the present patent application is.
The patent U.S. Pat. No. 5,185,595 describes a variant of a device for measuring the tension of a rock bolt. The design includes disc springs, but otherwise different design under patent to a significant extent from the structure in accordance with the present application. For example describes nothing about rock bolt other design in the patent. The design has been further major drawbacks of the rock bolt is not connected in parallel to the walls of the borehole. Further, construct a measuring device, the force that affect the rock bolt, which prevents mechanical assembly of the structure (roof bolt with a measuring device).
The patent DE8535263U1 describes a variation of an anchor bolt which comprises a wedge function in the end of the bolt. The construction in accordance with the patent differs to a significant extent from the construction in accordance with the present application. For example the construction expands only to a limited load, which means that it does not handle high load.
The patent U.S. Pat. No. 3,179,082 describes a variant of a bolt which is intended to be inserted in holes in rock, concrete or the like. Structure comprises an indicator with which the stress acting on the bolt indicated. The construction in accordance with the patent differs to a significant extent from the construction in accordance with the present application. The spring construction allows further that this charging energy which is released by rupture of the rock bolt. The construction is also sensitive to the drill testing of this include bolted joints. The construction of the patent is also not suitable for use on mechanical mounting. The construction can also be sensitive to cracks in the rock when it lacks the present rock bolt dual functions.
The patent U.S. Pat. No. 2,725,843 describes a variant of a rock bolt which is intended to be inserted into holes in the rock and the like. Structure comprises an indicator with which the stress acting on the bolt indicated. The construction in accordance with the patent differs to a significant extent from the construction in accordance with the present application. For example, the construction, according to the patent, lacks of reliability. The design probably needs molded solid to be reliable. Further includes the construction compression springs which can be dangerous in the event of breakage. The structure can also hardly be mounted by a machine.